Voltage drop, in integrated circuits (IC) refers to the resistance (R) encountered by the current (I) flowing through different parts of the IC. According to Ohm's Law, voltage (V) is proportional to current (I) and resistance (R) and is represented by the equation V=I*R. Thus, voltage drop measured across different portions of an IC is also commonly referred to as IR drop.
Generally, ICs with different circuitry and packaging configurations may experience different levels of voltage or IR drops at different parts of the circuitry. In other words, power distribution across an IC varies and may depend on the complexity of the circuitry or the packaging configuration. For instance, wirebond packages have power pads at the edges of the IC package surrounding the IC. There is usually a significant voltage drop as power travels from the edge of the IC package to the center of the IC chip. As such, the core of the IC chip, which is located farthest from the edges of the IC package, will experience the highest level of voltage drop while the periphery of the IC chip close to the edges of the IC package will experience the lowest level of voltage drop.
As voltage drop varies across different regions of the IC, circuit blocks with different speed requirements can be placed in different regions in order to optimize performance in the device. For instance, high speed circuit blocks usually have higher power consumption. Therefore, these blocks need to be placed in a lower voltage drop region. On the other hand, circuit blocks operating at a lower speed will have lower power consumption and need not be placed in a low voltage drop region.
Therefore, it is desirable to have a way to divide an IC into different regions based on measured voltage drop values. It is also desirable to have a way to map or place critical timing circuit blocks in specific regions to optimize the performance of a device. It is within this context that the invention arises.